Active Stylus with Filter Having a Threshold

ABSTRACT

In one embodiment, a method includes receiving at a stylus a receive signal from a device. The stylus includes one or more computer-readable media embodying logic, and the device includes a touch sensor. The receive signal is received at the stylus through the touch sensor of the device and one or more electrodes of the stylus. The method includes determining whether a level of the receive signal substantially meets or exceeds a pre-determined threshold; if the level of the receive signal substantially meets or exceeds the pre-determined threshold, then transmitting the receive signal to the logic for processing; and, if the level of the receive signal does not substantially meet or exceed the pre-determined threshold, then filtering out the receive signal from processing by the logic.

RELATED APPLICATION

This application claims the benefit, under 35 U.S.C. §119(e), of U.S.Provisional Patent Application No. 61/553,114, filed 28 Oct. 2011, whichis incorporated herein by reference.

TECHNICAL FIELD

This disclosure generally relates to touch sensors.

BACKGROUND

A touch sensor may detect the presence and location of a touch or theproximity of an object (such as a user's finger or a stylus) within atouch-sensitive area of the touch sensor overlaid on a display screen,for example. In a touch-sensitive-display application, the touch sensormay enable a user to interact directly with what is displayed on thescreen, rather than indirectly with a mouse or touch pad. A touch sensormay be attached to or provided as part of a desktop computer, laptopcomputer, tablet computer, personal digital assistant (PDA), smartphone,satellite navigation device, portable media player, portable gameconsole, kiosk computer, point-of-sale device, or other suitable device.A control panel on a household or other appliance may include a touchsensor.

There are a number of different types of touch sensors, such as, forexample, resistive touch screens, surface acoustic wave touch screens,and capacitive touch screens. Herein, reference to a touch sensor mayencompass a touch screen, and vice versa, where appropriate. When anobject touches or comes within proximity of the surface of thecapacitive touch screen, a change in capacitance may occur within thetouch screen at the location of the touch or proximity. A touch-sensorcontroller may process the change in capacitance to determine itsposition on the touch screen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example touch sensor with an example touch-sensorcontroller.

FIG. 2 illustrates an example active stylus exterior.

FIG. 3 illustrates an example active stylus interior.

FIG. 4 illustrates an example active stylus with touch sensor device.

FIG. 5 illustrates an example controller in an active stylus.

FIG. 6 illustrates an example method for adjusting a received signalthreshold in an active stylus.

FIG. 7 illustrates an example method for filtering a signal received byan active stylus.

FIG. 8 illustrates an example filter in an active stylus.

FIG. 9 illustrates an example method for filtering a signal received byan active stylus.

FIG. 10 illustrates an example filter in an active stylus.

FIG. 11 illustrates an example method for filtering a signal received byan active stylus.

FIG. 12 illustrates an example filter in an active stylus.

FIG. 13 illustrates an example method for filtering a signal received byan active stylus.

FIG. 14 illustrates an example method for transmitting a signal from anactive stylus to a device.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 illustrates an example touch sensor 10 with an exampletouch-sensor controller 12. Touch sensor 10 and touch-sensor controller12 may detect the presence and location of a touch or the proximity ofan object within a touch-sensitive area of touch sensor 10. Herein,reference to a touch sensor may encompass both the touch sensor and itstouch-sensor controller, where appropriate. Similarly, reference to atouch-sensor controller may encompass both the touch-sensor controllerand its touch sensor, where appropriate. Touch sensor 10 may include oneor more touch-sensitive areas, where appropriate. Touch sensor 10 mayinclude an array of drive and sense electrodes (or an array ofelectrodes of a single type) disposed on one or more substrates, whichmay be made of a dielectric material. Herein, reference to a touchsensor may encompass both the electrodes of the touch sensor and thesubstrate(s) that they are disposed on, where appropriate.Alternatively, where appropriate, reference to a touch sensor mayencompass the electrodes of the touch sensor, but not the substrate(s)that they are disposed on.

An electrode (whether a ground electrode, guard electrode, driveelectrode, or sense electrode) may be an area of conductive materialforming a shape, such as for example a disc, square, rectangle, thinline, other suitable shape, or suitable combination of these. One ormore cuts in one or more layers of conductive material may (at least inpart) create the shape of an electrode, and the area of the shape may(at least in part) be bounded by those cuts. In particular embodiments,the conductive material of an electrode may occupy approximately 100% ofthe area of its shape. As an example and not by way of limitation, anelectrode may be made of indium tin oxide (ITO) and the ITO of theelectrode may occupy approximately 100% of the area of its shape(sometimes referred to as a 100% fill), where appropriate. In particularembodiments, the conductive material of an electrode may occupysubstantially less than 100% of the area of its shape. As an example andnot by way of limitation, an electrode may be made of fine lines ofmetal or other conductive material (FLM), such as for example copper,silver, or a copper- or silver-based material, and the fine lines ofconductive material may occupy approximately 5% of the area of its shapein a hatched, mesh, or other suitable pattern. Herein, reference to FLMencompasses such material, where appropriate. Although this disclosuredescribes or illustrates particular electrodes made of particularconductive material forming particular shapes with particular fillpercentages having particular patterns, this disclosure contemplates anysuitable electrodes made of any suitable conductive material forming anysuitable shapes with any suitable fill percentages having any suitablepatterns.

Where appropriate, the shapes of the electrodes (or other elements) of atouch sensor may constitute in whole or in part one or moremacro-features of the touch sensor. One or more characteristics of theimplementation of those shapes (such as, for example, the conductivematerials, fills, or patterns within the shapes) may constitute in wholeor in part one or more micro-features of the touch sensor. One or moremacro-features of a touch sensor may determine one or morecharacteristics of its functionality, and one or more micro-features ofthe touch sensor may determine one or more optical features of the touchsensor, such as transmittance, refraction, or reflection.

A mechanical stack may contain the substrate (or multiple substrates)and the conductive material forming the drive or sense electrodes oftouch sensor 10. As an example and not by way of limitation, themechanical stack may include a first layer of optically clear adhesive(OCA) beneath a cover panel. The cover panel may be clear and made of aresilient material suitable for repeated touching, such as for exampleglass, polycarbonate, or poly(methyl methacrylate) (PMMA). Thisdisclosure contemplates any suitable cover panel made of any suitablematerial. The first layer of OCA may be disposed between the cover paneland the substrate with the conductive material forming the drive orsense electrodes. The mechanical stack may also include a second layerof OCA and a dielectric layer (which may be made of PET or anothersuitable material, similar to the substrate with the conductive materialforming the drive or sense electrodes). As an alternative, whereappropriate, a thin coating of a dielectric material may be appliedinstead of the second layer of OCA and the dielectric layer. The secondlayer of OCA may be disposed between the substrate with the conductivematerial making up the drive or sense electrodes and the dielectriclayer, and the dielectric layer may be disposed between the second layerof OCA and an air gap to a display of a device including touch sensor 10and touch-sensor controller 12. As an example only and not by way oflimitation, the cover panel may have a thickness of approximately 1 mm;the first layer of OCA may have a thickness of approximately 0.05 mm;the substrate with the conductive material forming the drive or senseelectrodes may have a thickness of approximately 0.05 mm; the secondlayer of OCA may have a thickness of approximately 0.05 mm; and thedielectric layer may have a thickness of approximately 0.05 mm. Althoughthis disclosure describes a particular mechanical stack with aparticular number of particular layers made of particular materials andhaving particular thicknesses, this disclosure contemplates any suitablemechanical stack with any suitable number of any suitable layers made ofany suitable materials and having any suitable thicknesses. As anexample and not by way of limitation, in particular embodiments, a layerof adhesive or dielectric may replace the dielectric layer, second layerof OCA, and air gap described above, with there being no air gap to thedisplay.

One or more portions of the substrate of touch sensor 10 may be made ofpolyethylene terephthalate (PET) or another suitable material. Thisdisclosure contemplates any suitable substrate with any suitableportions made of any suitable material. In particular embodiments, thedrive or sense electrodes in touch sensor 10 may be made of ITO in wholeor in part. In particular embodiments, the drive or sense electrodes intouch sensor 10 may be made of fine lines of metal or other conductivematerial. As an example and not by way of limitation, one or moreportions of the conductive material may be copper or copper-based andhave a thickness of approximately 5 μm or less and a width ofapproximately 10 μm or less. As another example, one or more portions ofthe conductive material may be silver or silver-based and similarly havea thickness of approximately 5 μm or less and a width of approximately10 μm or less. This disclosure contemplates any suitable electrodes madeof any suitable material.

Touch sensor 10 may implement a capacitive form of touch sensing. In amutual-capacitance implementation, touch sensor 10 may include an arrayof drive and sense electrodes forming an array of capacitive nodes. Adrive electrode and a sense electrode may form a capacitive node. Thedrive and sense electrodes forming the capacitive node may come neareach other, but not make electrical contact with each other. Instead,the drive and sense electrodes may be capacitively coupled to each otheracross a space between them. A pulsed or alternating voltage applied tothe drive electrode (by touch-sensor controller 12) may induce a chargeon the sense electrode, and the amount of charge induced may besusceptible to external influence (such as a touch or the proximity ofan object). When an object touches or comes within proximity of thecapacitive node, a change in capacitance may occur at the capacitivenode and touch-sensor controller 12 may measure the change incapacitance. By measuring changes in capacitance throughout the array,touch-sensor controller 12 may determine the position of the touch orproximity within the touch-sensitive area(s) of touch sensor 10.

In a self-capacitance implementation, touch sensor 10 may include anarray of electrodes of a single type that may each form a capacitivenode. When an object touches or comes within proximity of the capacitivenode, a change in self-capacitance may occur at the capacitive node andcontroller 12 may measure the change in capacitance, for example, as achange in the amount of charge needed to raise the voltage at thecapacitive node by a pre-determined amount. As with a mutual-capacitanceimplementation, by measuring changes in capacitance throughout thearray, controller 12 may determine the position of the touch orproximity within the touch-sensitive area(s) of touch sensor 10. Thisdisclosure contemplates any suitable form of capacitive touch sensing,where appropriate.

In particular embodiments, one or more drive electrodes may togetherform a drive line running horizontally or vertically or in any suitableorientation. Similarly, one or more sense electrodes may together form asense line running horizontally or vertically or in any suitableorientation. In particular embodiments, drive lines may runsubstantially perpendicular to sense lines. Herein, reference to a driveline may encompass one or more drive electrodes making up the driveline, and vice versa, where appropriate. Similarly, reference to a senseline may encompass one or more sense electrodes making up the senseline, and vice versa, where appropriate.

Touch sensor 10 may have drive and sense electrodes disposed in apattern on one side of a single substrate. In such a configuration, apair of drive and sense electrodes capacitively coupled to each otheracross a space between them may form a capacitive node. For aself-capacitance implementation, electrodes of only a single type may bedisposed in a pattern on a single substrate. In addition or as analternative to having drive and sense electrodes disposed in a patternon one side of a single substrate, touch sensor 10 may have driveelectrodes disposed in a pattern on one side of a substrate and senseelectrodes disposed in a pattern on another side of the substrate.Moreover, touch sensor 10 may have drive electrodes disposed in apattern on one side of one substrate and sense electrodes disposed in apattern on one side of another substrate. In such configurations, anintersection of a drive electrode and a sense electrode may form acapacitive node. Such an intersection may be a location where the driveelectrode and the sense electrode “cross” or come nearest each other intheir respective planes. The drive and sense electrodes do not makeelectrical contact with each other—instead they are capacitively coupledto each other across a dielectric at the intersection. Although thisdisclosure describes particular configurations of particular electrodesforming particular nodes, this disclosure contemplates any suitableconfiguration of any suitable electrodes forming any suitable nodes.Moreover, this disclosure contemplates any suitable electrodes disposedon any suitable number of any suitable substrates in any suitablepatterns.

As described above, a change in capacitance at a capacitive node oftouch sensor 10 may indicate a touch or proximity input at the positionof the capacitive node. Touch-sensor controller 12 may detect andprocess the change in capacitance to determine the presence and locationof the touch or proximity input. Touch-sensor controller 12 may thencommunicate information about the touch or proximity input to one ormore other components (such one or more central processing units (CPUs))of a device that includes touch sensor 10 and touch-sensor controller12, which may respond to the touch or proximity input by initiating afunction of the device (or an application running on the device).Although this disclosure describes a particular touch-sensor controllerhaving particular functionality with respect to a particular device anda particular touch sensor, this disclosure contemplates any suitabletouch-sensor controller having any suitable functionality with respectto any suitable device and any suitable touch sensor.

Touch-sensor controller 12 may be one or more integrated circuits (ICs),such as for example general-purpose microprocessors, microcontrollers,programmable logic devices (PLDs) or programmable logic arrays (PLAs),application-specific ICs (ASICs). In particular embodiments,touch-sensor controller 12 comprises analog circuitry, digital logic,and digital non-volatile memory. In particular embodiments, touch-sensorcontroller 12 is disposed on a flexible printed circuit (FPC) bonded tothe substrate of touch sensor 10, as described below. The FPC may beactive or passive, where appropriate. In particular embodiments multipletouch-sensor controllers 12 are disposed on the FPC. Touch-sensorcontroller 12 may include a processor unit, a drive unit, a sense unit,and a storage unit. The drive unit may supply drive signals to the driveelectrodes of touch sensor 10. The sense unit may sense charge at thecapacitive nodes of touch sensor 10 and provide measurement signals tothe processor unit representing capacitances at the capacitive nodes.The processor unit may control the supply of drive signals to the driveelectrodes by the drive unit and process measurement signals from thesense unit to detect and process the presence and location of a touch orproximity input within the touch-sensitive area(s) of touch sensor 10.The processor unit may also track changes in the position of a touch orproximity input within the touch-sensitive area(s) of touch sensor 10.The storage unit may store programming for execution by the processorunit, including programming for controlling the drive unit to supplydrive signals to the drive electrodes, programming for processingmeasurement signals from the sense unit, and other suitable programming,where appropriate. Although this disclosure describes a particulartouch-sensor controller having a particular implementation withparticular components, this disclosure contemplates any suitabletouch-sensor controller having any suitable implementation with anysuitable components.

Tracks 14 of conductive material disposed on the substrate of touchsensor 10 may couple the drive or sense electrodes of touch sensor 10 toconnection pads 16, also disposed on the substrate of touch sensor 10.As described below, connection pads 16 facilitate coupling of tracks 14to touch-sensor controller 12. Tracks 14 may extend into or around (e.g.at the edges of) the touch-sensitive area(s) of touch sensor 10.Particular tracks 14 may provide drive connections for couplingtouch-sensor controller 12 to drive electrodes of touch sensor 10,through which the drive unit of touch-sensor controller 12 may supplydrive signals to the drive electrodes. Other tracks 14 may provide senseconnections for coupling touch-sensor controller 12 to sense electrodesof touch sensor 10, through which the sense unit of touch-sensorcontroller 12 may sense charge at the capacitive nodes of touch sensor10. Tracks 14 may be made of fine lines of metal or other conductivematerial. As an example and not by way of limitation, the conductivematerial of tracks 14 may be copper or copper-based and have a width ofapproximately 100 μm or less. As another example, the conductivematerial of tracks 14 may be silver or silver-based and have a width ofapproximately 100 μm or less. In particular embodiments, tracks 14 maybe made of ITO in whole or in part in addition or as an alternative tofine lines of metal or other conductive material. Although thisdisclosure describes particular tracks made of particular materials withparticular widths, this disclosure contemplates any suitable tracks madeof any suitable materials with any suitable widths. In addition totracks 14, touch sensor 10 may include one or more ground linesterminating at a ground connector (which may be a connection pad 16) atan edge of the substrate of touch sensor 10 (similar to tracks 14).

Connection pads 16 may be located along one or more edges of thesubstrate, outside the touch-sensitive area(s) of touch sensor 10. Asdescribed above, touch-sensor controller 12 may be on an FPC. Connectionpads 16 may be made of the same material as tracks 14 and may be bondedto the FPC using an anisotropic conductive film (ACF). Connection 18 mayinclude conductive lines on the FPC coupling touch-sensor controller 12to connection pads 16, in turn coupling touch-sensor controller 12 totracks 14 and to the drive or sense electrodes of touch sensor 10. Inanother embodiment, connection pads 16 may be connected to anelectro-mechanical connector (such as a zero insertion forcewire-to-board connector); in this embodiment, connection 18 may not needto include an FPC. This disclosure contemplates any suitable connection18 between touch-sensor controller 12 and touch sensor 10.

FIG. 2 illustrates an example exterior of an example active stylus 20.Active stylus 20 may include one or more components, such as buttons 30or sliders 32 and 34 integrated with an outer body 22. These externalcomponents may provide for interaction between active stylus 20 and auser or between a device and a user. As an example and not by way oflimitation, interactions may include communication between active stylus20 and a device, enabling or altering functionality of active stylus 20or a device, or providing feedback to or accepting input from one ormore users. The device may by any suitable device, such as, for exampleand without limitation, a desktop computer, laptop computer, tabletcomputer, personal digital assistant (PDA), smartphone, satellitenavigation device, portable media player, portable game console, kioskcomputer, point-of-sale device, or other suitable device. Although thisdisclosure provides specific examples of particular componentsconfigured to provide particular interactions, this disclosurecontemplates any suitable component configured to provide any suitableinteraction. Active stylus 20 may have any suitable dimensions withouter body 22 made of any suitable material or combination of materials,such as, for example and without limitation, plastic or metal. Inparticular embodiments, exterior components (e.g. 30 or 32) of activestylus 20 may interact with internal components or programming of activestylus 20 or may initiate one or more interactions with one or moredevices or other active styluses 20.

As described above, actuating one or more particular components mayinitiate an interaction between active stylus 20 and a user or betweenthe device and the user. Components of active stylus 20 may include oneor more buttons 30 or one or more sliders 32 and 34. As an example andnot by way of limitation, buttons 30 or sliders 32 and 34 may bemechanical or capacitive and may function as a roller, trackball, orwheel. As another example, one or more sliders 32 or 34 may function asa vertical slider 34 aligned along a longitudinal axis, while one ormore wheel sliders 32 may be aligned along the circumference of activestylus 20. In particular embodiments, capacitive sliders 32 and 34 orbuttons 30 may be implemented using one or more touch-sensitive areas.Touch-sensitive areas may have any suitable shape, dimensions, location,or be made from any suitable material. As an example and not by way oflimitation, sliders 32 and 34 or buttons 30 may be implemented usingareas of flexible mesh formed using lines of conductive material. Asanother example, sliders 32 and 34 or buttons 30 may be implementedusing a FPC.

Active stylus 20 may have one or more components configured to providefeedback to or accepting feedback from a user, such as, for example andwithout limitation, tactile, visual, or audio feedback. Active stylus 20may include one or more ridges or grooves 24 on its outer body 22.Ridges or grooves 24 may have any suitable dimensions, have any suitablespacing between ridges or grooves, or be located at any suitable area onouter body 22 of active stylus 20. As an example and not by way oflimitation, ridges 24 may enhance a user's grip on outer body 22 ofactive stylus 20 or provide tactile feedback to or accept tactile inputfrom a user. Active stylus 20 may include one or more audio components38 capable of transmitting and receiving audio signals. As an exampleand not by way of limitation, audio component 38 may contain amicrophone capable of recording or transmitting one or more users'voices. As another example, audio component 38 may provide an auditoryindication of a power status of active stylus 20. Active stylus 20 mayinclude one or more visual feedback components 36, such as alight-emitting diode (LED) indicator. As an example and not by way oflimitation, visual feedback component 36 may indicate a power status ofactive stylus 20 to the user.

One or more modified surface areas 40 may form one or more components onouter body 22 of active stylus 20. Properties of modified surface areas40 may be different than properties of the remaining surface of outerbody 22. As an example and not by way of limitation, modified surfacearea 40 may be modified to have a different texture, temperature, orelectromagnetic characteristic relative to the surface properties of theremainder of outer body 22. Modified surface area 40 may be capable ofdynamically altering its properties, for example by using hapticinterfaces or rendering techniques. A user may interact with modifiedsurface area 40 to provide any suitable functionally. For example andnot by way of limitation, dragging a finger across modified surface area40 may initiate an interaction, such as data transfer, between activestylus 20 and a device.

One or more components of active stylus 20 may be configured tocommunicate data between active stylus 20 and the device. For example,active stylus 20 may include one or more tips 26 or nibs. Tip 26 mayinclude one or more electrodes configured to communicate data betweenactive stylus 20 and one or more devices or other active styluses. Tip26 may be made of any suitable material, such as a conductive material,and have any suitable dimensions, such as, for example, a diameter of 1mm or less at its terminal end. Active stylus 20 may include one or moreports 28 located at any suitable location on outer body 22 of activestylus 20. Port 28 may be configured to transfer signals or informationbetween active stylus 20 and one or more devices or power sources. Port28 may transfer signals or information by any suitable technology, suchas, for example, by universal serial bus (USB) or Ethernet connections.Although this disclosure describes and illustrates a particularconfiguration of particular components with particular locations,dimensions, composition and functionality, this disclosure contemplatesany suitable configuration of suitable components with any suitablelocations, dimensions, composition, and functionality with respect toactive stylus 20.

FIG. 3 illustrates an example internal components of example activestylus 20. Active stylus 20 may include one or more internal components,such as a controller 50, sensors 42, memory 44, or power source 48. Inparticular embodiments, one or more internal components may beconfigured to provide for interaction between active stylus 20 and auser or between a device and a user. In other particular embodiments,one or more internal components, in conjunction with one or moreexternal components described above, may be configured to provideinteraction between active stylus 20 and a user or between a device anda user. As an example and not by way of limitation, interactions mayinclude communication between active stylus 20 and a device, enabling oraltering functionality of active stylus 20 or a device, or providingfeedback to or accepting input from one or more users.

Controller 50 may be a microcontroller or any other type of processorsuitable for controlling the operation of active stylus 20. Controller50 may be one or more ICs—such as, for example, general-purposemicroprocessors, microcontrollers, PLDs, PLAs, or ASICs. Controller 50may include a processor unit, a drive unit, a sense unit, and a storageunit. The drive unit may supply signals to electrodes of tip 26 throughcenter shaft 41. The drive unit may also supply signals to control ordrive sensors 42 or one or more external components of active stylus 20.The sense unit may sense signals received by electrodes of tip 26through center shaft 41 and provide measurement signals to the processorunit representing input from a device. The sense unit may also sensesignals generated by sensors 42 or one or more external components andprovide measurement signals to the processor unit representing inputfrom a user. The processor unit may control the supply of signals to theelectrodes of tip 26 and process measurement signals from the sense unitto detect and process input from the device. The processor unit may alsoprocess measurement signals from sensors 42 or one or more externalcomponents. The storage unit may store programming for execution by theprocessor unit, including programming for controlling the drive unit tosupply signals to the electrodes of tip 26, programming for processingmeasurement signals from the sense unit corresponding to input from thedevice, programming for processing measurement signals from sensors 42or external components to initiate a pre-determined function or gestureto be performed by active stylus 20 or the device, and other suitableprogramming, where appropriate. As an example and not by way oflimitation, programming executed by controller 50 may electronicallyfilter signals received from the sense unit. Although this disclosuredescribes a particular controller 50 having a particular implementationwith particular components, this disclosure contemplates any suitablecontroller having any suitable implementation with any suitablecomponents.

In particular embodiments, active stylus 20 may include one or moresensors 42, such as touch sensors, gyroscopes, accelerometers, contactsensors, or any other type of sensor that detect or measure data aboutthe environment in which active stylus 20 operates. Sensors 42 maydetect and measure one or more characteristic of active stylus 20, suchas acceleration or movement, orientation, contact, pressure on outerbody 22, force on tip 26, vibration, or any other suitablecharacteristic of active stylus 20. As an example and not by way oflimitation, sensors 42 may be implemented mechanically, electronically,or capacitively. As described above, data detected or measured bysensors 42 communicated to controller 50 may initiate a pre-determinedfunction or gesture to be performed by active stylus 20 or the device.In particular embodiments, data detected or received by sensors 42 maybe stored in memory 44. Memory 44 may be any form of memory suitable forstoring data in active stylus 20. In other particular embodiments,controller 50 may access data stored in memory 44. As an example and notby way of limitation, memory 44 may store programming for execution bythe processor unit of controller 50. As another example, data measuredby sensors 42 may be processed by controller 50 and stored in memory 44.

Power source 48 may be any type of stored-energy source, includingelectrical or chemical-energy sources, suitable for powering theoperation of active stylus 20. In particular embodiments, power source48 may be charged by energy from a user or device. As an example and notby way of limitation, power source 48 may be a rechargeable battery thatmay be charged by motion induced on active stylus 20. In otherparticular embodiments, power source 48 of active stylus 20 may providepower to or receive power from the device. As an example and not by wayof limitation, power may be inductively transferred between power source48 and a power source of the device.

FIG. 4 illustrates an example active stylus 20 with an example device52. Device 52 may have a display (not shown) and a touch sensor with atouch-sensitive area 54. Device 52 display may be a liquid crystaldisplay (LCD), a LED display, a LED-backlight LCD, or other suitabledisplay and may be visible though a cover panel and substrate (and thedrive and sense electrodes of the touch sensor disposed on it) of device52. Although this disclosure describes a particular device display andparticular display types, this disclosure contemplates any suitabledevice display and any suitable display types.

Device 52 electronics may provide the functionality of device 52. Asexample and not by way of limitation, device 52 electronics may includecircuitry or other electronics for wireless communication to or fromdevice 52, execute programming on device 52, generating graphical orother user interfaces (UIs) for device 52 display to display to a user,managing power to device 52 from a battery or other power source, takingstill pictures, recording video, other suitable functionality, or anysuitable combination of these. Although this disclosure describesparticular device electronics providing particular functionality of aparticular device, this disclosure contemplates any suitable deviceelectronics providing any suitable functionality of any suitable device.

In particular embodiments, active stylus 20 and device 52 may besynchronized prior to communication of data between active stylus 20 anddevice 52. As an example and not by way of limitation, active stylus 20may be synchronized to device through a pre-determined bit sequencetransmitted by the touch sensor of device 52. As another example, activestylus 20 may be synchronized to device by processing the drive signaltransmitted by drive electrodes of the touch sensor of device 52. Activestylus 20 may interact or communicate with device 52 when active stylus20 is brought in contact with or in proximity to touch-sensitive area 54of the touch sensor of device 52. In particular embodiments, interactionbetween active stylus 20 and device 52 may be capacitive or inductive.As an example and not by way of limitation, when active stylus 20 isbrought in contact with or in the proximity of touch-sensitive area 54of device 52, signals generated by active stylus 20 may influencecapacitive nodes of touch-sensitive area of device 52 or vice versa. Asanother example, a power source of active stylus 20 may be inductivelycharged through the touch sensor of device 52, or vice versa. Althoughthis disclosure describes particular interactions and communicationsbetween active stylus 20 and device 52, this disclosure contemplates anysuitable interactions and communications through any suitable means,such as mechanical forces, current, voltage, or electromagnetic fields.

In particular embodiments, measurement signal from the sensors of activestylus 20 may initiate, provide for, or terminate interactions betweenactive stylus 20 and one or more devices 52 or one or more users, asdescribed above. Interaction between active stylus 20 and device 52 mayoccur when active stylus 20 is contacting or in proximity to device 52.As an example and not by way of limitation, a user may perform a gestureor sequence of gestures, such as shaking or inverting active stylus 20,whilst active stylus 20 is hovering above touch-sensitive area 54 ofdevice 52. Active stylus may interact with device 52 based on thegesture performed with active stylus 20 to initiate a pre-determinedfunction, such as authenticating a user associated with active stylus 20or device 52. Although this disclosure describes particular movementsproviding particular types of interactions between active stylus 20 anddevice 52, this disclosure contemplates any suitable movementinfluencing any suitable interaction in any suitable way.

Active stylus 20 may receive signals from external sources, includingdevice 52, a user, or another active stylus. Active stylus 20 mayencounter noise when receiving such signals. As examples, noise may beintroduced into the received signals from data quantization, limitationsof position-calculation algorithms, bandwidth limitations of measurementhardware, accuracy limitations of analog front ends of devices withwhich active stylus 20 communicates, the physical layout of the system,sensor noise, charger noise, device noise, stylus circuitry noise, orexternal noise. The overall noise external to active stylus 20 may havefrequency characteristics covering a wide range of the spectrum,including narrow band noise and wide band noise, as well.

Active stylus 20 may transmit signals based in part on the determinationthat it has received a signal, and not simply noise, from a signalsource. As an example, active stylus 20 may determine whether it hasreceived a signal from device 52 by comparing the received signal to asignal threshold. If the received signal satisfies the thresholdrequirement (e.g., meets the minimum value of this signal threshold),active stylus 20 may process the received signal, including, forexample, amplifying or phase-shifting the received signal, in order tocreate a transmit signal to transmit back to device 52 via electrodes intip 26. If the received signal does not satisfy the thresholdrequirement, active stylus 20 may not process the received signalfurther. In particular embodiments, logic in active stylus 20 including,for example, a comparator (either alone or in combination with or aspart of a processor), determines whether the threshold is met by thereceived signal. If the threshold is met, the received signal may besent to additional logic for processing including, for example,filtering of the received signal. The additional logic may be, withoutlimitation, a processor, a controller (and in particular embodiments,the same controller or processor may contain the logic and theadditional logic), or analog circuitry. If the threshold is not met, thereceived signal may not be sent to the additional logic for processing.It may be desirable for active stylus 20 to, for example, dynamicallyadjust the threshold for determining that a received signal contains asignal from device 52, or any other signal source, and not merely noise.As an example, if the signal threshold is too low, active stylus 20 mayincorrectly determine that a pure noise signal is actually a signal fromdevice 52, proceed to process the noise signal, and incorrectly transmita response signal. As another example, if signal threshold is too high,active stylus 20 may incorrectly determine that a signal from device 52is purely a noise signal and fail to process the received signal andtransmit a response signal. The threshold adjustment may be based onsome factors and may be done dynamically.

FIG. 5 illustrates an example controller 50, which may be incorporatedin an active stylus (e.g., active stylus 20). In particular embodiments,a signal S is received by one or more electrodes capable of sensingsignals in active stylus 20. These electrodes may reside on activestylus tip 26. The signal S received by the electrodes in active stylus20 may then be transmitted from the electrodes to controller 50. Inparticular embodiments, signal S is transmitted to controller 50 viacenter shaft 41. Controller 50, as discussed above, may include, withoutlimitation, a drive unit, a sense unit, a storage unit, and a processorunit. The components illustrated in FIG. 5 may reside in controller 50,and in certain embodiments may be a part of the processor unit ofcontroller 50.

In particular embodiments including the one illustrated by FIG. 5,received signal S may be amplified by an amplifier 100. Amplifier 100may be any suitable amplifier, including a digital or an analogamplifier. After the signal S is amplified, it may be filtered by afilter 200. In some embodiments, filter 200 may be an analog filterincluding analog circuit components, such as one or more resistors,capacitors, or inductors. In other embodiments, filter 200 may be adigital filter, such as a finite-impulse-response (FIR) filter, or aKalman filter implemented, for example, on a processor. Filter 200 maybe any suitable filter for any type of processing of the received signal(e.g., signal S), including, for example, a filter for noise removal.Filter 200 may be, for example and without limitation, a low passfilter, a band pass filter, or a high pass filter. In particularembodiments, filter 200 may be a band pass filter whose frequencycharacteristics are designed to attenuate noise and amplify a signal.Filter 200 may also be used to boost signal strength of the receivedsignal at active stylus 20.

Referring to FIG. 5, amplified and/or filtered signal S, denotedS_filter, proceeds to control processor 300. Control processor 300 maybe a microcontroller. Control processor 300 includes comparator 310 andprocessor 320. Comparator 310 may, in particular embodiments, be ananalog comparator, including analog circuitry. In other embodiments,comparator 310 may be a digital comparator, and in yet otherembodiments, comparator 310 may be a processor. Comparator 310 receivesas input S_filter. Comparator 310 then compares S_filter to at least onesignal threshold to determine whether S_filter represents noise alone ora received signal in addition to noise. As an example, if S_filter is avoltage, comparator 310 compares S_filter to a voltage threshold valueV_th to determine whether S_filter is less than, equal to, or greaterthan V_th. In this example, if S_filter is equal to or greater thanV_th, comparator 310 determines that S_filter contains a signal, and notmerely noise, and outputs this determination to processor 320 via outputline 330. In particular embodiments, if S_filter meets or exceeds thesignal threshold V_th, processor 320 may then output S_filter forfurther processing by active stylus 20. In addition to having a signalthreshold V_th, comparator 310 may also have a threshold for diagnosticpurposes. As an example, comparator 310 may have a second threshold,V_diag, with a value different from V_th, and the output of a comparisonof S_filter and V_diag is sent to processor 320 via output line 340. Inthis example, the determination by comparator 310 whether S_filter meetsor exceeds signal threshold V_th controls whether or not S_filter isprocessed further by active stylus 20, and the determination whetherS_filter meets or exceeds diagnostic threshold V_diag allows processor320 to determine future values of V_th or V_diag.

In the example embodiment of FIG. 5, comparator 310 may also outputadditional data to processor 320. Comparator 310 may analyze S_filterand output any type of information about S_filter to processor 320 viaoutput line 340. As an example, comparator 310 may calculate thesignal-to-noise ratio (SNR) of S_filter and send this information toprocessor 320. As another example, comparator 310 may determine theamplitude characteristics of S_filter and send this to processor 320. Asyet another example, comparator 310 may determine the frequencycharacteristics of S_filter, including the bandwidth of S_filter, andsend this to processor 320. As yet another example, comparator 310 maydetermine the phase characteristics of S_filter and send this toprocessor 320. Output line 340 may carry one or more signals containingany type of relevant information about S_filter from comparator 310 toprocessor 320.

As illustrated in the example embodiment of FIG. 5, processor 320receives data from comparator 310 via output lines 330 and 340.Processor 320 may adjust threshold V_th or V_diag based on the datareceived from comparator 310. Additionally, processor 320 may adjustV_th or V_diag based on data received from any other components ofactive stylus 20, including other parts of controller 50 (such as thesense unit, drive unit, storage unit, or processor unit), memory 44,power source 48, or sensors 42. Processor 320 may send adjustedthreshold values of V_th and V_diag to comparator 310 via output line350. Additionally, processor 320 may send other types of data tocomparator 310 via output line 350 or additional output lines,including, for example, SNR cutoff values. Although FIG. 5 illustrates aparticular embodiment in which processor 320 receives data fromcomparator 310, processor 320 may also receive data from or send data toany part of active stylus 20. As an example, processor 320 may receivedata regarding known characteristics (such as bandwidth, frequency,phase, amplitude, or synchronization patterns) of the signal of interesttransmitted by a signal source such as device 52. As another example,processor 320 may receive data regarding the mode in which active stylus20 is operating (such as, for example, a hover mode).

In particular embodiments, processor 320 may adjust V_th so that V_th isapproximately proportional to the SNR of S_filter. As an example, if theSNR of S_filter is high, as may be the case when active stylus 20 isnear to a signal source like device 52, processor 320 may adjust V_thupward, so that the new value of V_th is higher than the old value ofV_th. This may allow for improved noise rejection by active stylus 20.As another example, if the SNR of S_filter is low or if the amplitude ofS_filter is low, as may be the case when active stylus 20 is far from asignal source like device 52, processor 320 may adjust V_th downward, sothat the new value of V_th is lower than the old value of V_th. This mayallow for improved signal detection by active stylus 20 in low SNR orlow amplitude situations.

In other embodiments, if processor 320 determines that comparator 310 isfalsely triggering too frequently on S_filter (that is, if comparator310 too frequently incorrectly determines that S_filter contains asignal when S_filter is purely noise), processor 320 may increase V_thto improve noise rejection. False triggering may occur more frequentlyin very low SNR situations where the amplitude or frequencycharacteristics of the noise are comparable to those of the signal.Thus, in particular embodiments, processor 320 may reduce V_th in lowSNR situations until some minimum value of V_th is reached (where falsetriggering occurs too frequently), at which point processor 320 mayincrease V_th to prevent further false triggering. In other embodiments,processor 320 may reduce V_th in low SNR situations until some minimumSNR value for S_filter is reached (such as, for example, an SNR of 1),at which point processor 320 may increase V_th to prevent further falsetriggering.

In yet other embodiments, if processor 320 determines that comparator310 is too frequently incorrectly rejecting S_filter as purely noise,processor 320 may decrease V_th to improve signal detection. Thus, inparticular embodiments, processor 320 may increase V_th until somemaximum value of V_th is reached (for example, where signal rejectionoccurs too frequently), at which point processor 320 may decrease V_thto prevent further signal rejection.

Processor 320 may use diagnostic threshold V_diag to determine if activestylus is operating in a low SNR range. For example, if V_th is set to 2volts, V_diag is set to 1.5 volts, and S_filter is consistently in therange between 1.5 and 2 volts (without meeting or exceeding 2 volts),comparator 310 will reject S_filter as a noise signal. Processor 320,however, may have data indicating that S_filter is not pure noise(based, for example, on known characteristics of the signal transmittedby device 52). Processor 320 may analyze the fact that S_filter meetsthe diagnostic threshold, V_diag, and not the signal detectionthreshold, V_th, and determine that active stylus 20 is operating in alow SNR range.

In addition to analyzing current data from comparator 310 and other datasources from active stylus 20, processor 320 may access storedinformation. As an example, processor 320 may access prior data valuesreceived from comparator 310 (such as threshold comparison outputs, SNRof S_filter, or amplitude of S_filter) or other components of activestylus 20 to determine future values of V_th or V_diag. Prior datavalues accessed by processor 320 may, for example, be stored inprocessor 320 or in memory 44. Initial or prior values for V_th orV_diag may also be accessed or stored by processor 320.

FIG. 6 illustrates an example method for dynamically adjusting a signaldetection threshold in active stylus 20. The method may start at step600, where a signal received by active stylus 20 is accessed. Withreference again to FIG. 5, in particular embodiments, this step mayoccur when control processor 300 receives S_filter from filter 200. Atstep 610, one or more characteristics of the signal are determined. Inparticular embodiments, this step may occur in control processor 300,with certain characteristics determined by comparator 310 (including,for example, whether a threshold is met) and certain characteristicsdetermined by processor 320 (including, for example, SNR). In particularembodiments, one of the characteristics determined for the signal iswhether the signal satisfies the threshold requirement based on thecurrent value of the threshold. This may be determined by comparing thesignal to the current value of the threshold. At step 620, a thresholdis adjusted based on the one or more characteristics of the signal. Thismay result in the threshold having a new value. In particularembodiments, the steps illustrated in FIG. 6 may be repeated any numberof times (e.g., any number of iterations). For example, during a seconditeration, a second signal may be received (returning back to step 600).One or more characteristics may be determined for the second signal atstep 610. Again, one of the characteristics determined for the secondsignal is whether the second signal satisfies the threshold requirementbased on the current value of the threshold. Note that the current valueof the threshold may have been adjusted during the previous iteration.At step 620, the threshold may be adjusted again based on thecharacteristics of the second signal.

In particular embodiments, processor 320 adjusts signal detectionthreshold V_th based on data received from comparator 310 and sendsadjusted V_th to comparator 310 via output line 350. In this manner,comparator 310, output lines 330 and 340, processor 320, and output line350 form a feedback loop for controlling the one or more signalthresholds against which S_filter is compared. Particular embodimentsmay repeat the steps of the method of FIG. 6, where appropriate.Moreover, although this disclosure describes and illustrates particularsteps of the method of FIG. 6 as occurring in a particular order, thisdisclosure contemplates any suitable steps of the method of FIG. 6occurring in any suitable order. Furthermore, although this disclosuredescribes and illustrates particular components, devices, or systemscarrying out particular steps of the method of FIG. 6, this disclosurecontemplates any suitable combination of any suitable components,devices, or systems carrying out any suitable steps of the method ofFIG. 6.

FIG. 7 illustrates an example method for filtering a signal received byactive stylus 20. The method may start at step 700, where a signalreceived by active stylus 20 is accessed. With reference again to FIG.5, in particular embodiments, this step may occur when filter 200receives signal S from amplifier 100. At step 710, the signal S isprocessed by filter 200. The output of filter 200, S_filter, may then befurther processed by controller 50 or any other component of activestylus 20. In particular embodiments, no output S_filter is providedwhen certain conditions of filter 200 (for example, a threshold) are notmet. Particular embodiments may repeat the steps of the method of FIG.7, where appropriate. Moreover, although this disclosure describes andillustrates particular steps of the method of FIG. 7 as occurring in aparticular order, this disclosure contemplates any suitable steps of themethod of FIG. 7 occurring in any suitable order. Furthermore, althoughthis disclosure describes and illustrates particular components,devices, or systems carrying out particular steps of the method of FIG.7, this disclosure contemplates any suitable combination of any suitablecomponents, devices, or systems carrying out any suitable steps of themethod of FIG. 7.

As illustrated in the example embodiment of FIG. 8, active stylus 20 mayhave a filter 200 (or one or more filters that comprise filter 200) witha signal detection threshold 800. In one embodiment, if the receivedsignal S does not meet or exceed the minimum signal detection threshold800, filter 200 will not output a signal for further processing. Thatis, S_filter will have a value of 0 or, alternatively, will not beoutput by filter 200. This allows filter 200 to reject signals that maybe noise rather than a communication from, for example, device 52.Filter 200 may have a threshold 800 that is dynamically assigned oradjusted. Additionally, filter 200 may have a threshold 800 that isbased on the signal-to-noise ration (SNR) of received signal S, on themode of operation of active stylus 20, or any other quantity that activestylus 20 has access to.

FIG. 9 illustrates an example method for filtering, with a threshold, asignal received by active stylus 20. The method may start at step 900,where a signal received by active stylus 20 is accessed. With referenceagain to FIG. 5, in particular embodiments, this step may occur whenfilter 200 receives signal S from amplifier 100. At step 910, the signalS is processed by filter 200 having a threshold 800. At step 920, ifreceived signal S meets or exceeds threshold 800, then the output offilter 200, S_filter, may then be further processed by controller 50 orany other component of active stylus 20. In particular embodiments, whenreceived signal S does not meet or exceed threshold 800, no output fromfilter 200, S_filter, is provided to controller 50 (or, in particularembodiments, a signal of value 0 is provided). Particular embodimentsmay repeat the steps of the method of FIG. 9, where appropriate.Moreover, although this disclosure describes and illustrates particularsteps of the method of FIG. 9 as occurring in a particular order, thisdisclosure contemplates any suitable steps of the method of FIG. 9occurring in any suitable order. Furthermore, although this disclosuredescribes and illustrates particular components, devices, or systemscarrying out particular steps of the method of FIG. 9, this disclosurecontemplates any suitable combination of any suitable components,devices, or systems carrying out any suitable steps of the method ofFIG. 9.

FIG. 10 illustrates an example embodiment of active stylus 20 with afilter 200 with the characteristic of a non-linear gain. Although FIG.10 depicts filter 200 with threshold 1000, filter 200 may have anon-linear gain without having threshold 1000. As an example of anon-linear gain, when the amplitude of received signal S is abovethreshold 1000 but still near threshold 1000, the gain (in particularembodiments, the ratio of S_filter to S) may be proportionally higherthan when the amplitude of received signal S is more significantly abovethreshold 1000. This is illustrated in FIG. 10, where at location 1010,the gain of filter 200 is proportionally higher than for higher valuesof received signal S. The parameters of filter 200 may be adjusted inany number of ways, including, for example, having more nonlinearregions like location 1010 in the filter, to ensure that input signal Shas the desired gain level applied to it depending on the value of S.This type of filter 200 may be useful in situations when active stylus20 is in between drive lines of device 52, causing the amplitude of thereceived signal S to be low. As an example, if the amplitude of thereceived signal S is low but active stylus 20 must still transmit withsufficient power to be properly detected by device 52, a non-linear gainmay be desirable.

FIG. 11 illustrates an example method for filtering, with a non-lineargain, a signal received by active stylus 20. The method may start atstep 1100, where a signal received by active stylus 20 is accessed. Withreference again to FIG. 5, in particular embodiments, this step mayoccur when filter 200 receives signal S from amplifier 100. The signal Sis processed by filter 200 having a non-linear gain, as typified by thefilter output value S_filter at location 1010. At step 1110, anon-linear function of the received signal S may be computed (or, inparticular embodiments, may be predetermined), and at step 1120, theoutput of filter 200, S_filter, may then be further processed bycontroller 50 or any other component of active stylus 20. In particularembodiments, with threshold 1000, when received signal S does not meetor exceed threshold 1000, no output from filter 200, S_filter, isprovided to controller 50 (or, in particular embodiments, a signal ofvalue 0 is provided). Particular embodiments may repeat the steps of themethod of FIG. 11, where appropriate. Moreover, although this disclosuredescribes and illustrates particular steps of the method of FIG. 11 asoccurring in a particular order, this disclosure contemplates anysuitable steps of the method of FIG. 11 occurring in any suitable order.Furthermore, although this disclosure describes and illustratesparticular components, devices, or systems carrying out particular stepsof the method of FIG. 11, this disclosure contemplates any suitablecombination of any suitable components, devices, or systems carrying outany suitable steps of the method of FIG. 11.

FIG. 12 illustrates an example embodiment of active stylus 20 withfilter 200 having the characteristic of a proportional gain. AlthoughFIG. 12 depicts filter 200 without a threshold, filter 200 may have aproportional gain with a threshold. The value of the output of filter200, S_filter, is proportional to the value of the received signal S.The parameters of filter 200 may be adjusted in any number of ways,including, for example, having a higher or lower proportional gain (orratio of S_filter to S) to ensure that input signal S has the desiredproportional gain level applied to it depending on the value of S. Inparticular embodiments, the signal transmitted from active stylus 20 todevice 52 is a function of the signal S received by active stylus. Thus,a filter 200 with a proportional gain, as illustrated in FIG. 12, may beuseful in situations when transmitting a signal proportional to thereceived signal is desirable. As an example, if active stylus 20 isclose to device 52, it may be desirable for active stylus to transmitproportionally to the signal S that it receives, rather thantransmitting at a high and constant energy level, in order to ensurethat device 52 to be able to more accurately detect the location ofactive stylus 20.

FIG. 13 illustrates an example method for filtering, with a proportionalgain, a signal received by active stylus 20. The method may start atstep 1300, where a signal received by active stylus 20 is accessed. Withreference again to FIG. 5, in particular embodiments, this step mayoccur when filter 200 receives signal S from amplifier 100. At step1310, the signal S is processed by filter 200 having a proportionalgain, with filter output value S_filter being proportional to filterinput S. A proportional function of the received signal S is computed(or, in particular embodiments, may be predetermined), and at step 1320,the output of filter 200, S_filter, may then be further processed bycontroller 50 or any other component of active stylus 20. In particularembodiments, output from filter 200, S_filter, is provided to controller50, and active stylus 20 may transmit a signal proportional to receivedsignal S. Particular embodiments may repeat the steps of the method ofFIG. 13, where appropriate. Moreover, although this disclosure describesand illustrates particular steps of the method of FIG. 13 as occurringin a particular order, this disclosure contemplates any suitable stepsof the method of FIG. 13 occurring in any suitable order. Furthermore,although this disclosure describes and illustrates particularcomponents, devices, or systems carrying out particular steps of themethod of FIG. 13, this disclosure contemplates any suitable combinationof any suitable components, devices, or systems carrying out anysuitable steps of the method of FIG. 13.

Active stylus 20 may transmit a signal to device 52 based on the signalS that active stylus 20 received from device 52. In particularembodiments, the signal transmitted from active stylus 20 to device 52is a function of the signal S received by active stylus, including, forexample, a function of S_filter (itself a function of received signalS). FIG. 14 illustrates an example method for transmitting a signal fromactive stylus 20 to device 52 based on the signal S received by activestylus 20. The method may start at step 1400, where a signal received byactive stylus 20 is accessed. With reference again to FIG. 5, inparticular embodiments, this step may occur when filter 200 receivessignal S from amplifier 100. At step 1410, received signal S is comparedto first and second pre-determined thresholds. In particularembodiments, one or both of these thresholds may be a threshold (such asthreshold 800 or threshold 1000) of filter 200, but in otherembodiments, the first or second thresholds may be independent of anythresholds of filter 200. The first or second thresholds may be staticpre-determined thresholds or dynamic pre-determined thresholds, and maybe set by controller 50 or any other component of active stylus 20. Atstep 1420, a determination is made as to whether some characteristic ofsignal S, such as, for example, an amplitude of signal S, exceeds thefirst pre-determined threshold. If the amplitude of signal S does notexceed the first pre-determined threshold, then the method returns tostep 1400, where another signal received by active stylus 20 isaccessed, and the method restarts. If the amplitude of signal S doesexceed the first pre-determined threshold, then the method proceeds tostep 1430, where a determination is made as to whether the samecharacteristic of signal S, such as, for example, an amplitude of signalS, exceeds the second pre-determined threshold. If the amplitude ofsignal S does not exceed the second pre-determined threshold, then themethod proceeds to step 1440, where active stylus 20 transmits a signalof fixed amplitude to device 52. In particular embodiments, the signaltransmitted is a maximum-amplitude signal that may enable betterperformance of active stylus 20 in modes such as hover mode. If, at step1430, the amplitude of signal S exceeds the second pre-determinedthreshold, then the method proceeds to step 1450, where active stylus 20transmits a signal that is a function of the filtered version of signalS, S_filter. In particular embodiments, the function of S_filter may benon-linear. In yet other embodiments, the function of S_filter may be aphase change of S_filter or a multiplicative gain applied S_filter. Inyet other embodiments, active stylus 20 may take one action if both thefirst and second thresholds are exceeded, and a second action if onlythe first (and not the second) threshold is exceeded, including, but notlimited to, transmitting different types of signals to device 52. Asanother example, active stylus 20 may filter or process signal Sdifferently based on the specific combination of thresholds exceeded.Active stylus 20 may have more than two thresholds, and more than twotypes of actions that are taken based on the combination of thresholdsexceeded. Particular embodiments may repeat the steps of the method ofFIG. 14, where appropriate. Moreover, although this disclosure describesand illustrates particular steps of the method of FIG. 14 as occurringin a particular order, this disclosure contemplates any suitable stepsof the method of FIG. 14 occurring in any suitable order. Furthermore,although this disclosure describes and illustrates particularcomponents, devices, or systems carrying out particular steps of themethod of FIG. 14, this disclosure contemplates any suitable combinationof any suitable components, devices, or systems carrying out anysuitable steps of the method of FIG. 14.

Active stylus 20 may transmit a signal to device 52 based on input fromsensors 42 of active stylus 20. As an example, and without limitation,if a pressure sensor, one type of sensor that may comprise sensors 42,determines that active stylus 20 is touching device 52, then activestylus 20 may transmit a signal to device 52 that is a function of thereceived signal S (or, in other embodiments, a function of filteredreceived signal S_filter). In other embodiments, active stylus 20 maytransmit a signal that is a function of received signal S (or filteredreceived signal S_filter) based on controller 50 determining that activestylus 20 is touching device 52. In yet other embodiments, active stylus20 may receive data from device 52 that allows active stylus 20 todetermine that active stylus 20 and device 52 are in physical contact,such that active stylus 20 transmits a signal that is a function of S orS_filter to device 52.

Any of the filters 200 described in this disclosure may be used inconjunction with any suitable components or algorithms for active stylus20, including, without limitation, the use of dynamic received-signalthreshold adjustment or the use of dynamic electrode reconfiguration.The parameters of filter 200 may, in particular embodiments, be adjustedby controller 50 (or any other component of active stylus 20) based onoperating characteristics of active stylus 20 or characteristics ofreceived signal S, including SNR. In particular embodiments, either asingle filter or a combination of multiple filters (e.g., of differenttypes) may be incorporated in active stylus 20 for processing thereceived signal.

Herein, reference to a computer-readable non-transitory storage mediumencompasses a semiconductor-based or other integrated circuit (IC)(such, as for example, a field-programmable gate array (FPGA) or anapplication-specific IC (ASIC)), a hard disk, an HDD, a hybrid harddrive (HHD), an optical disc, an optical disc drive (ODD), amagneto-optical disc, a magneto-optical drive, a floppy disk, a floppydisk drive (FDD), magnetic tape, a holographic storage medium, asolid-state drive (SSD), a RAM-drive, a SECURE DIGITAL card, a SECUREDIGITAL drive, or another suitable computer-readable non-transitorystorage medium or a combination of two or more of these, whereappropriate. A computer-readable non-transitory storage medium may bevolatile, non-volatile, or a combination of volatile and non-volatile,where appropriate.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise by context. Therefore, herein, “A or B”means “A, B, or both,” unless expressly indicated otherwise or indicatedotherwise by context. Moreover, “and” is both joint and several, unlessexpressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A and B” means “A and B, jointly or severally,”unless expressly indicated otherwise or indicated otherwise by context.

This disclosure encompasses all changes, substitutions, variations,alterations, and modifications to the example embodiments herein that aperson having ordinary skill in the art would comprehend. Moreover,reference in the appended claims to an apparatus or system or acomponent of an apparatus or system being adapted to, arranged to,capable of, configured to, enabled to, operable to, or operative toperform a particular function encompasses that apparatus, system,component, whether or not it or that particular function is activated,turned on, or unlocked, as long as that apparatus, system, or componentis so adapted, arranged, capable, configured, enabled, operable, oroperative.

What is claimed is:
 1. A method comprising: receiving at a stylus areceive signal from a device, the stylus comprising one or morecomputer-readable non-transitory storage media embodying logic, thedevice comprising a touch sensor, the receive signal being received atthe stylus through the touch sensor of the device and one or moreelectrodes of the stylus; determining whether a level of the receivesignal substantially meets or exceeds a pre-determined threshold; if thelevel of the receive signal substantially meets or exceeds thepre-determined threshold, then transmitting the receive signal to thelogic for processing; and if the level of the receive signal does notsubstantially meet or exceed the pre-determined threshold, thenfiltering out the receive signal from processing by the logic.
 2. Themethod of claim 1, wherein one or more of the electrodes of the stylusare disposed on or in a tip of the stylus.
 3. The method of claim 1,wherein the pre-determined threshold is dynamically adjusted.
 4. Themethod of claim 3, wherein the pre-determined threshold is dynamicallyadjusted based at least in part on the level of the receive signal. 5.The method of claim 1, wherein the processing by the logic comprisesfiltering the receive signal.
 6. The method of claim 1, furthercomprising transmitting from an electrode of the stylus a transmitsignal that is a function of the receive signal.
 7. One or morecomputer-readable non-transitory storage media embodying first logicthat is operable when executed to: receive a receive signal transmittedfrom a device to a stylus, the stylus comprising the media, the mediafurther embodying second logic, the device comprising a touch sensor,the receive signal being received at the stylus through the touch sensorof the device and one or more electrodes of the stylus; determinewhether a level of the receive signal substantially meets or exceeds apre-determined threshold; if the level of the receive signalsubstantially meets or exceeds the pre-determined threshold, thentransmit the receive signal to the second logic for processing; and ifthe level of the receive signal does not substantially meet or exceedthe pre-determined threshold, then filter out the receive signal fromprocessing by the second logic.
 8. The media of claim 7, wherein one ormore of the electrodes of the stylus are disposed on or in a tip of thestylus.
 9. The media of claim 7, wherein the pre-determined threshold isdynamically adjusted.
 10. The media of claim 9, wherein thepre-determined threshold is dynamically adjusted based at least in parton the level of the receive signal.
 11. The media of claim 7, whereinthe processing by the second logic comprises filtering the receivesignal.
 12. The media of claim 7, wherein the second logic is operableto cause to be transmitted from an electrode of the stylus a transmitsignal that is a function of the receive signal.
 13. The media of claim7, wherein a comparator embodies the first logic.
 14. The media of claim7, wherein a controller or analog circuitry embodies the second logic.15. The media of claim 7, wherein a controller embodies the first logicand the second logic.
 16. The media of claim 7, wherein a singlecontroller comprises all the media.
 17. A stylus comprising: one or moreelectrodes; and one or more computer-readable non-transitory storagemedia embodying: first logic that is operable when executed to: receivea receive signal transmitted from a device to a stylus, the styluscomprising the media, the media further embodying second logic, thedevice comprising a touch sensor, the receive signal being received atthe stylus through the touch sensor of the device and one or moreelectrodes of the stylus; determining whether a level of the receivesignal substantially meets or exceeds a pre-determined threshold; if thelevel of the receive signal substantially meets or exceeds thepre-determined threshold, then transmitting the receive signal to thesecond logic for processing; and if the level of the receive signal doesnot substantially meet or exceed the pre-determined threshold, thenfiltering out the receive signal from processing by the second logic.18. The stylus of claim 17, wherein the pre-determined threshold isdynamically adjusted.
 19. The stylus of claim 18, wherein thepre-determined threshold is dynamically adjusted based at least in parton the level of the receive signal.
 20. The stylus of claim 17, whereinthe processing by the second logic comprises filtering the receivesignal.